As for what ores you're looking for...
The best of the best is specifically called out when you find it. You can't mistake it for anything else. When you find it, you'll know.
Steel is complicated to make. You're looking for magnetite, limonite, and hematite, all 3 of which will turn to iron when smelted, and marble, chalk, dolomite, limestone, and calcite, all 5 of which are forms of flux. 1 iron bar + 1 flux stone + 1 fuel (in addition to the fuel it takes to run the reaction) turns into 1 pig iron bar. 1 pig iron bar + 1 iron bar + 1 flux stone + 1 fuel (again, in addition to the fuel to react) turns into 2 steel bars. All told, you're looking at 2 iron, 2 flux, and 2-4 fuel per 2 steel bars.
Silver is the ideal material for hammers and maces and is found in the forms of galena, tetrahedrite, horn silver, and native silver.
Bronze is generally believed to be the second-best "common" metal for weapons and armor. You're looking for copper, which is found in the forms of tetrahedrite, malachite, and native copper, as well as tin, which is found in the form of cassiterite. One copper ore and one cassiterite, or one copper bar and one tin bar, will make 2 bronze bars.
Bismuth bronze, which is just as good as normal bronze except more valuable, takes 2 copper bars, 1 tin bar, and 1 bismuth bar to make. Bismuth is found in the form of bismuthinite.
Iron is worse than bronze, and, as mentioned above, is found in the forms of magnetite, hematite, and limonite.
Copper is the worst weapons-grade material and, again, is found in tetrahedrite, malachite, and native copper.